Comparison of creatine kinase elevation caused by Janus kinase inhibitors and interleukin-6 inhibitors in patients with rheumatoid arthritis: A propensity score-matched study.

Objectives: This study aimed to examine whether creatine kinase (CK) elevation occurs with interleukin (IL)-6 inhibitors, as in Janus kinase (JAK) inhibitors, which are reported to increase CK levels in rheumatoid arthritis. Patients and methods: A multicenter database of JAK inhibitor and IL-6 inhibitor treatment was retrospectively searched between January 2016 to December 2022; 142 cases (117 females, 25 males, mean age: 63.8±13.0 years; range, 20 to 85 years), with 71 cases in each group, were extracted by propensity score matching using age, sex, body mass index, and CK at 0 weeks. The outlier rate was compared. Patients' background characteristics related to elevated CK levels at 24 weeks were investigated by univariate and multivariate analyses. Results: Creatine kinase levels at 4 and 12 weeks were significantly higher with JAK inhibitors than with IL-6 inhibitors (four weeks, 72 vs. 87.5 IU/mL, p=0.016; 12 weeks, 71 vs. 95.5 IU/mL, p=0.028). The outlier rate (Grade 1) with JAK inhibitors increased significantly over time (0 weeks, 4.2%; four weeks, 18.1%; 12 weeks, 21.7%; 24 weeks, 18.3%; p=0.015), whereas that with IL-6 inhibitors increased slightly (0 weeks, 5.6%; four weeks, 9.2%; 12 weeks, 8.6%; 24 weeks, 8.5%; p=0.745), with a significant difference between the groups (p=0.035). No patients discontinued treatment due to myalgia or renal dysfunction. The factors significantly positively related to elevated CK levels at 24 weeks were male sex and creatinine. Those significantly negatively related were Steinbrocker stage and class, modified health assessment questionnaire scores, estimated glomerular filtration rate, and glucocorticoid dose. Conclusion: Mild CK elevations with JAK inhibitors are not a particular clinical problem. CK elevation might be specific to JAK inhibitors.

Biologic and targeted synthetic disease-modifying anti-rheumatic drugs improve body composition in rheumatoid arthritis patients more than conventional synthetic disease-modifying anti-rheumatic drugs: Results from the PRESENT study.

INTRODUCTION: The effects of biologic and targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs) and conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) on body composition and muscle function in rheumatoid arthritis (RA) patients requiring treatment enhancement were compared. METHODS: This multicenter, prospective, observational study (PRESENT Study) divided RA patients non-randomly into a csDMARD group (n = 100) and a b/tsDMARD group (n = 100). Changes in body composition and muscle function were examined in 80 patients in each group followed for 52 weeks. The percentages of new-onset and improved sarcopenia over 1 year were investigated. Patients in the b/tsDMARD group were divided into three groups by drug type: TNF inhibitors (n = 30), non-TNF inhibitors (n = 23), and JAK inhibitors (n = 27). RESULTS: Baseline median age and disease duration were 70.0 and 4.0 years, respectively. Changes in weight (24 and 52 weeks) and muscle mass (52 weeks) were significantly higher in the b/tsDMARD group (p = .035, p < .001, and p = .002, respectively). On multivariate logistic regression analysis, b/tsDMARD treatment (OR 3.21, p = .002), DAS28-ESR (OR 0.65 p = .011), and muscle mass (OR 0.90, p = .023) were independently associated with increased muscle mass at 52 weeks. The percentages of new-onset and improved sarcopenia were almost equal. There were no significant differences in the time-dependent changes (52 weeks) of clinical status, body composition, muscle function, and status of sarcopenia among TNF inhibitors, non-TNF inhibitors, and JAK inhibitors. CONCLUSIONS: Weight and muscle mass increased significantly more with b/tsDMARD than with csDMARD treatment. There were no differences in body composition changes by mode of action with b/tsDMARDs.

Efficacy and safety of Janus kinase inhibitors in patients with difficult-to-treat rheumatoid arthritis.

OBJECTIVES: This study evaluated the effectiveness of Janus kinase inhibitors (JAKi) in patients with difficult-to-treat rheumatoid arthritis (D2T RA). METHODS: This study included 220 patients with RA who were treated with JAKi. Sixty-two patients were naïve to biological disease-modifying anti-rheumatic drugs (bDMARDs)/JAKi (1st group), 57 patients were failure to one bDMARDs/JAKi (2nd group), and 101 patients were failure to ≥ 2 bDMARDs/JAKi. Of these 101 patients, 25 did not meet the D2T RA criteria (non-D2T RA group) and 76 met the D2T RA criteria (D2T RA group). RESULTS: : DAS28-ESR was improved in all groups at 24 weeks (1st: p<0.01, 2nd: p<0.01, non-D2T RA: p=0.01, D2TRA: p=0.02), and improvement ratio of DAS28-ESR was not different between DT2RA group and 2nd (p=0.73) or non-D2T RA group (p=0.68). Glucocorticoid use (odds ratios: 8.67; 95% CI: 1.23-60.90; P=0.03) and number of past bDMARD/JAKi uses ≥ 3 (odds ratios: 10.55; 95% CI: 1.39-80.30; P=0.02) were risk factors for DAS28-ESR ≥ 3.2 at 24 weeks in the D2T RA group. CONCLUSIONS: Clinical efficacy of JAKi in D2T RA group did not differ from that in 2nd and non-D2T RA groups. Glucocorticoid use and multiple bDMARD/JAKi failure were poor prognostic factors for D2T RA.

Ultrasonographic Synovitis Is Associated with the Development of Joint Destruction in Patients with Psoriatic Arthritis.

BACKGROUND: Psoriatic arthritis (PsA) is characterized by enthesitis. As persistent inflammation around joints results in bone and cartilage destruction and physical impairment, a detailed assessment of inflammation is essential. We previously reported the difference between clinical assessment (tenderness) and ultrasound (US) assessment (inflammation) of entheses. Herein, we investigated whether clinical or US assessment of joints and entheses can predict the progression of joint destruction in Japanese patients with PsA. METHODS: Thirty joints and 14 entheses in 47 patients were assessed using US and clinical examination. The US greyscale (GS) and power Doppler (PD) scores at the ultrasonographic synovitis, the US active enthesitis count, and the clinical tender joint/entheses count were assessed. Additionally, the yearly radiographic progression of the Sharp-van der Heijde scoring method for PsA was assessed. Their correlations were investigated. RESULTS: About half of the patients with PsA experienced joint destruction during a follow-up period of 20.4 months. Progression of joint destruction in patients with PsA only correlated with joint GS and PD scores, reflecting the severity of ultrasonographic synovitis, not with the tender joint/entheses count. CONCLUSIONS: US examinations are essential for preventing joint destruction and physical impairment in patients with PsA.

The bioimpedance phase angle may be associated with frailty in rheumatoid arthritis patients: Results from a prospective, cohort study.

OBJECTIVES: This study investigated whether the phase angle (PhA) on bioelectrical impedance analysis is related to frailty in rheumatoid arthritis (RA) patients. METHODS: Data from a prospective cohort study of RA patients were analysed. The PhA was assessed by the bioelectrical impedance analysis method, and frailty was assessed by the Kihon Check List (KCL) annually. The cut-off value of the PhA for frailty was calculated by receiver-operating characteristic analysis. The relationships between the PhA and frailty were evaluated by logistic regression analysis. The relationships between the change in PhA and frailty status and the KCL score were evaluated by analysis of covariance and multiple regression analysis. RESULTS: A total of 170 patients (81.2% female, 66.2 ± 13.1 years) were included in the analysis. A PhA of less than the cut-off for frailty was significantly associated with frailty (odds ratio: 4.75, 95% confidence interval: 1.86, 12.17). The change in the PhA was significantly associated with the change in the KCL score (ß = -0.15). In robust patients, there was a significant difference in the rate of change of the PhA between the group that became pre-frail in the next year and the group that remained robust. CONCLUSIONS: The PhA may be associated with frailty in RA patients.

Incidence of new carotid plaques in rheumatoid arthritis patients: 6-Year prospective results of the TOMORROW study.

OBJECTIVES: The purpose of this study was to evaluate the new incidence of carotid plaques in rheumatoid arthritis (RA) patients over a 6-year prospective follow-up and to assess the risk factors. METHODS: This is a 10-year prospective cohort study that included 208 RA patients and 205 age- and gender-matched controls. Ultrasound assessment of the bilateral carotid arteries was performed in 2011 and 2017. RESULTS: There were no differences in the incidence of new carotid atherosclerotic plaques over 6 years between the two groups (35.5% vs. 37.0%, respectively; p = .936). The mean Disease Activity Score 28-C-reactive protein over 6 years in RA patients was 2.73 ± 0.95. Multiple logistic regression analysis showed that RA was not a risk factor for new carotid atherosclerotic plaques (odds ratios, 0.708; 95% confidence interval, 0.348-1.440; p = .340). An average glucocorticoid dose of >1.8 mg/day over 6 years was a risk factor for new carotid atherosclerotic plaques (odds ratios, 8.54; 95% confidence interval, 1.641-44.455; p = .011). CONCLUSIONS: Incidence of new carotid atherosclerotic plaques was similar between well-controlled disease activity RA patients and control subjects. A mean glucocorticoid dose of >1.8 mg/day over 6 years was a risk factor for new carotid atherosclerotic plaques.

Neck pain and related factors in patients with rheumatoid arthritis.

OBJECTIVES: In rheumatoid arthritis, neck pain can be caused by inflammatory reactions or cervical lesions, but the prevalence and associated factors have not been well studied. This study aimed to investigate the prevalence of neck pain in patients with rheumatoid arthritis and elucidate the related factors. METHODS: This study included 146 patients with rheumatoid arthritis. Neck pain, quality of life, and levels of anxiety and depression were evaluated using a questionnaire. Cervical lesions and spinal alignment were evaluated using plain radiograph and magnetic resonance imaging. Factors associated with neck pain were analysed using a logistic regression model. RESULTS: Fifty-six per cent of the patients had neck pain, and the quality of life scores were significantly worse in these patients. Multivariate analysis revealed age, C7 sagittal vertical axis, upper cervical lesion, and endplate erosion as factors associated with neck pain in patients with rheumatoid arthritis. CONCLUSIONS: More than half the patients with rheumatoid arthritis suffer from neck pain, and neck pain affects the quality of life and activities of daily living. Neck pain was associated with upper cervical lesion and endplate erosion suggesting the importance of radiological examination in patients with rheumatoid arthritis and neck pain.

Comparison of clinical and radiographic results of mobile-bearing total ankle arthroplasty between osteoarthritis and rheumatoid arthritis.

OBJECTIVES: Clinical results of mobile-bearing total ankle arthroplasty (TAA) for rheumatoid arthritis (RA) have been reported, but no studies have compared osteoarthritis (OA) and RA. Clinical and radiographic outcomes after at least 3 years were compared between OA and RA. METHODS: Eleven ankles with OA and 22 ankles with RA were followed after mobile-bearing TAA (FINE total ankle system). Clinical outcomes were assessed by the American Orthopaedic Foot and Ankle Society (AOFAS) score. Radiographic outcomes were evaluated by the angular position of the implant, radiolucent lines, migration, and subsidence. Operative and postoperative complications were assessed. RESULTS: There were no significant differences in clinical outcomes, radiographic outcomes, or complications, except the final follow-up AOFAS total score (OA: 89.4 vs RA: 78.2; p = .044) and pain score (OA: 37.3 vs RA: 30.5; p = .041) at a mean follow-up of 83.4 months. Delayed wound healing occurred in 9.1% in RA and none in OA. Radiolucent lines were observed in 45% of both groups, and implant removal was performed in 9.1% and 18.2% of OA and RA, respectively; there were no significant differences. CONCLUSIONS: The final follow-up AOFAS total score and pain score were significantly higher in OA after the FINE total ankle system. There was a discrepancy between radiographic abnormalities and implant removal in both OA and RA.

Impact of disease burden or inflammation on nutritional assessment by the GLIM criteria in female patients with rheumatoid arthritis.

BACKGROUND & AIMS: In 2018, the Global Leadership Initiative on Malnutrition (GLIM) released a global standard for evaluating malnutrition. The etiologies of malnutrition in the GLIM criteria includes disease burden/inflammation, but how this view affects nutritional assessment remains unclear. This study aimed to investigate the impact of disease burden/inflammation on the proportion of malnourished patients defined by GLIM criteria, and how differences in methods for determining disease burden/inflammation in GLIM criteria affect existing nutritional indices among patients with rheumatoid arthritis (RA). We also investigated factors associated with malnutrition in RA patients. METHODS: Data from 135 female RA patients (66.8 ± 12.6 years) were cross-sectionally analyzed. Among the etiologies of malnutrition, disease burden/inflammation was defined as: (1) moderate or higher disease activity score (disease activity score composite of the 28-joint score and erythrocyte sedimentation rate [DAS28-ESR] ≥ 3.2) [DAS-malnutrition (MN)]; (2) elevated C-reactive protein (CRP) ≥0.5 mg/dL (CRP-MN); and (3) presence of RA (RA-MN). In each of the three conditions, nutritional indicators between well-nourished and malnourished groups were compared by analysis of covariance. Factors associated with malnutrition were analyzed with logistic regression analysis. RESULTS: The frequencies of malnutrition as defined by DAS-MN, CRP-MN, and RA-MN were 39%, 30%, and 71%, respectively. When malnutrition was defined by the DAS-MN and/or the CRP-MN, grip strength and serum ceruloplasmin, iron, and zinc levels showed significant differences between the well-nourished and malnourished groups (p < 0.05). The use of targeted synthetic or biological disease-modifying antirheumatic drugs (ts-/b-DMARD) (OR = 0.29; 95% CI 0.11-0.82), grip strength (OR = 0.83; 95% CI 0.75-0.91), subjective reduction in walking speed (OR = 5.24; 1.85-14.86) were significantly associated with malnutrition as determined by DAS-MN. CONCLUSION: Differences in disease burden/inflammation affect nutritional assessments. The number of malnourished patients with RA was negatively associated with the use of ts-/b-DMARDs and high physical function in women.

Risk factors for poor response to denosumab treatment in Japanese postmenopausal women with osteoporosis.

INTRODUCTION: Denosumab has been reported to increase bone mineral density (BMD) and suppress fractures, but poor responders are not uncommon. This study aimed to identify risk factors for poor response to denosumab treatment. This is the first study to explore risk factors for poor response to denosumab. MATERIALS AND METHODS: This retrospective observational study investigated 227 Japanese postmenopausal women who received denosumab with monitoring of BMD by dual-energy X-ray absorptiometry at 6-month intervals. Risk factors were identified using Cox's proportional hazard modeling. Poor responders were defined as not exceeding the least significant change of BMD from baseline for 3 years. RESULTS: Mean relative change from baseline for 3 years in lumbar spine (LS)-BMD, femoral neck (FN)-BMD, and total hip (TH)-BMD were 12.6%, 6.8%, and 6.1%, respectively. Numbers of poor responders were 10 in LS-BMD, 47 in FN-BMD, 38 in TH-BMD. Risk factors for poor response were concomitant glucocorticoid use for LS-BMD, low body mass index or initiation at higher BMD for FN-BMD, and pretreatment with bisphosphonates or initiation at higher BMD for TH-BMD. CONCLUSION: Risk factors for insufficient denosumab effect differed between BMD measurement sites. These results should be taken into consideration when selecting denosumab in clinical practice.

The bioimpedance phase angle is more useful than sarcopenia as a predictor of falls in patients with rheumatoid arthritis: Results from a 2-y prospective cohort study.

OBJECTIVES: The phase angle (PhA) is an index derived by bioelectrical impedance analysis that reflects the fragility of cell membranes, muscle mass, muscle strength, and nutritional status, and a decrease in PhA might be associated with falls. This study aimed to investigate the relationships of the PhA with sarcopenia and falls in patients with rheumatoid arthritis (RA). METHODS: Data from a prospective cohort study of 189 patients with RA (age 66.5 ± 13.3 y; 80% women) were analyzed. PhA, muscle mass, and grip strength (GS) were evaluated. Sarcopenia was assessed using the Asian Working Group for Sarcopenia 2014 criteria. The correlation between PhA and GS was investigated, and the cutoff value of the PhA for falls during a 2-y period was estimated with a receiver operating characteristic curve analysis. The effects of the PhA and sarcopenia on falls were examined with a Cox proportional hazards model. RESULTS: Of the 189 patients, 48 (25.4%) had falls. The PhA was significantly positively correlated with GS (r = 0.58; P < 0.001). The cutoff values for the PhA for falls were 4.06° for women and 5.26° for men. In the Cox proportional hazards model adjusted for sex, age, disease activity, glucocorticoid use, and activities of daily living at baseline, the hazard ratio for falls was significantly higher when the PhA was below the cutoff value at baseline (hazard ratio: 2.29; 95% confidence interval, 1.18-4.45). Sarcopenia was not a significant risk factor for falls. CONCLUSIONS: The PhA might be a useful surrogate marker to predict falls in patients with RA.

A case of successful radiofrequency catheter ablation for atrial tachycardia originating from the inferior vena cava using high-resolution mapping.

A 60-year-old man presented with sustained supraventricular tachycardia. Atrial tachycardia (AT), with the earliest atrial activation (EAA) occurring at the ostium of the coronary sinus, was reproducibly induced. Three-dimensional electroanatomical mapping (3DEAM) using a 3.5-mm distal electrode tip linear catheter (Thermocool) and radiofrequency energy (RF) was performed at the fractionated atrial electrogram site. It preceded at 30 ms to the EAA but did not terminate AT. Further 3DEAM using a multielectrode mapping catheter (Pentaray) demonstrated a centrifugal propagation pattern at the boundary zone between the right atrium and inferior vena cava. RF application here terminated AT, which then became non-inducible.

Risk factors for low back pain increase in rheumatoid arthritis: Analysis of a 7-year follow-up study.

OBJECTIVE: Several studies have demonstrated that low back pain (LBP) is related to disease activity in patients with rheumatoid arthritis (RA). However, there is no longitudinal research. This study aimed to determine the impacts and risk factors for LBP increase in RA in a longitudinal cohort study. METHODS: The study evaluated 113 patients with RA who completed the secondary survey. LBP increase was defined as ≥1 standard deviation of mean change in visual analogue scale (VAS) between the baseline and secondary surveys. The impacts of LBP increase on quality of life (QOL) and psychological status were evaluated. Risk factors were assessed among patient demographic characteristics and radiological changes. RESULTS: Mean change in VAS for LBP was -0.8 ± 30.4 mm during a mean 7-year follow-up. LBP increase was defined as ≥30-mm increase in VAS for LBP. Patients with LBP increase had significantly lower QOL and worse mental status than patients without it. Poor control of RA was identified as an independent risk factor for LBP increase (odds ratio, 9.82, p = .001). CONCLUSION: Patients with poor control of RA were likely to experience LBP increase in the long term. Control of RA disease activity is important for control of LBP, QOL, and mental status.

Incidence of and risk factors for spondylolisthesis, scoliosis, and vertebral fracture in rheumatoid arthritis.

INTRODUCTION: Although lumbar lesions such as spondylolisthesis, scoliosis, and vertebral fracture are not specific to rheumatoid arthritis (RA), the prevalence is high in RA patients. However, no longitudinal study has evaluated lumbar lesions in RA. This study aimed to investigate the incidence of and risk factors for lumbar lesions in RA by a prospective longitudinal cohort study. MATERIALS AND METHODS: The study cohort comprised 110 patients with RA from the 'analysis of factors for RA spinal disorders (AFFORD)' study who completed the secondary survey at a single orthopaedic outpatient RA clinic. Radiological examination included standing radiographs and magnetic resonance imaging (MRI) of the lumbar spine. New development of spondylolisthesis, scoliosis, and vertebral fracture were assessed between baseline and secondary survey. RESULTS: The incidences of spondylolisthesis, scoliosis, and vertebral fracture were 42%, 16%, and 12%, respectively, during a mean follow-up of 7 years. The independent risk factor for de novo scoliosis was poor control of RA (adjusted odds ratio [aOR] 4.81, p = 0.011), while the independent risk factors for new vertebral fracture was use of glucocorticoid at secondary survey (aOR 14.87, p = 0.012). Patients with de novo scoliosis exhibited more severe low back pain and lower quality of life than those without. CONCLUSION: The incidence of scoliosis was related in patients with poor control of RA, while new vertebral fracture was more common in patients with use of glucocorticoid. Control of disease activity might be important in preventing radiological lumbar disorders in RA.

Double-blinded randomized controlled trial to reveal the effects of Brazilian propolis intake on rheumatoid arthritis disease activity index; BeeDAI.

BACKGROUND AND AIMS: Brazilian propolis reportedly contributed to suppressing disease activity in a mouse model of rheumatoid arthritis (RA), suggesting new treatment options using Brazilian propolis. However, only results from animal experiments have been available, and the suppressive effects of Brazilian propolis on disease activity in humans with RA remain unknown. The purpose of this study was to clinically validate how Brazilian propolis intake changes disease activity in RA patients. METHODS: This study was conducted as a multicenter, double-blinded, randomized, placebo-controlled, parallel-group study of 80 women with RA (median age, 61.5 years; interquartile range, 56.0 to 67.3 years) showing moderate disease activity on Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). Test tablets containing Brazilian propolis were used in Group P (40 patients), and Brazilian propolis-free placebo tablets were used as control in Group C (40 patients). Group P received 5 tablets of propolis (508.5 mg of propolis) daily, and Group C received 5 tablets of placebo daily. The intervention lasted 24 weeks, with change in DAS28-ESR set as the primary endpoint. As secondary endpoints, other disease activity assessment (DAS28 using C-reactive protein, simplified disease activity index, clinical disease activity index), ultrasonographic evaluation of synovitis, activities of daily living, quality of life, changes in cytokine levels, and adverse events over the course of the study were also assessed. Data were statistically analyzed by analysis of covariance. RESULTS: No significant differences in the primary endpoint were identified between groups (Group P vs Group C, effect: 0.14, 95% confidence interval: -0.21 to 0.49, p = 0.427). Likewise, no significant differences were seen between groups for any secondary endpoints. The adverse event rate during the study period was 28% in Group P and 33% in Group C. CONCLUSIONS: Brazilian propolis exerted no effects on disease activity in patients with RA.

Change in dietary inflammatory index score is associated with control of long-term rheumatoid arthritis disease activity in a Japanese cohort: the TOMORROW study.

BACKGROUND: The dietary inflammatory index (DII®), a quantitative measure of the inflammatory potential of daily food and nutrient intake, and associations between a variety of health outcomes have been reported. However, the association between DII score and disease activity of rheumatoid arthritis (RA) is unclear. Therefore, this study was designed to test whether higher DII score contributes to disease activity and as a corollary, whether reducing DII score helps to achieve or maintain low disease activity or remission in patients with RA. METHODS: We performed a cross-sectional and longitudinal analysis using 6 years of data (from 2011 to 2017) in TOMORROW, a cohort study consisting of 208 RA patients and 205 gender- and age-matched controls started in 2010. Disease activity of RA patients was assessed annually using DAS28-ESR (disease activity score 28 joints and the erythrocyte sedimentation rate) as a composite measure based on arthritic symptoms in 28 joints plus global health assessment and ESR. Dietary data were collected in 2011 and 2017 using the brief-type self-administered diet history questionnaire (BDHQ). Energy-adjusted DII (E-DII™) score was calculated using 26 nutrients derived from the BDHQ. Data were analyzed with two-group comparisons, correlation analysis, and multivariable logistic regression analysis. RESULTS: One hundred and seventy-seven RA patients and 183 controls, for whom clinical and dietary survey data were available, were analyzed. RA patients had significantly higher E-DII (pro-inflammatory) score compared to controls both in 2011 and 2017 (p < 0.05). In RA patients, E-DII score was not a factor associated with significant change in disease activity. However, anti-inflammatory change in E-DII score was associated maintaining low disease activity (DAS28-ESR ≤ 3.2) or less for 6 years (OR 3.46, 95% CI 0.33-8.98, p = 0.011). CONCLUSIONS: The diets of RA patients had a higher inflammatory potential than controls. Although E-DII score was not a factor associated with significant disease activity change, anti-inflammatory change in E-DII score appeared to be associated with maintaining low disease activity in patients with RA. TRIAL REGISTRATION: UMIN Clinical Trials Registry, UMIN000003876 . Registered 7 Aug 2010-retrospectively registered.

Change in skeletal muscle mass is associated with lipid profiles in female rheumatoid arthritis patients -TOMORROW study.

BACKGROUND & AIMS: To examine the relationship between changes in skeletal muscle mass and lipid metabolism and glycometabolism in patients with rheumatoid arthritis (RA). METHODS: Data were analyzed from 148 female RA patients and 145 age-matched non-RA (control) female subjects from a prospective cohort study (TOMORROW; TOtal Management Of Risk factors in Rheumatoid arthritis patients to lOWer morbidity and mortality study). Appendicular skeletal muscle mass (ASM) was assessed using dual-energy x-ray absorptiometry and skeletal muscle mass index (SMI) was calculated as ASM divided by the square of height. The reference value for SMI in Asian women, 5.4 kg/m2, was used to define low SMI. Data were assessed using cross-sectional (2010 baseline data) and longitudinal (change in value from 2010 to 2013) methods from the retrospective cohort. RESULTS: At baseline in RA patients, the low SMI group showed significantly higher low-density lipoprotein cholesterol (LDL-chol) (p = 0.015), apolipoprotein (Apo)B (p = 0.046), and ApoB-to-A1 (ApoB/A1) (p = 0.025) than the normal SMI group. In multiple regression analysis of RA patients, sequential changes from 2010 to 2013 (Δ) in SMI and ApoB and ApoC2 showed significant negative relationships (ß = -0.19, -0.18, respectively) even after adjusting for age, RA duration, exercise habits, medication for RA, disease severity, activities of daily living (ADL) and body fat mass. No significant relation was evident between ΔSMI and various glycometabolism parameters in RA patients. CONCLUSIONS: Skeletal muscle mass might be related to lipid metabolism in RA patients. This relationship is independent of factors such as disease severity and body fat mass.